1. Field of the Invention
The invention relates to a method of winding optical fiber on a bobbin and, more particularly, to a method of winding optical fiber on a bobbin which permits free streaming of the fiber from the bobbin without clumping or knotting and which minimizes the effect on the optical signal passing through the fiber
2. Description of Related Art
A number of weapons and communications systems have been developed or are under development which use an optical fiber for two-way data communication between two or more moving bodies or between a moving body and a fixed station. Examples of such uses include communications links between aircraft, between an aircraft and a ship, and between a projectile, such as a missile or mortar shell, and a control station at its launch site. As an example of the latter use, see applicant's concurrently filed, co-pending U.S. patent application, Ser. No. 32,448, filed Mar. 31, 1987. Use of optical fiber for such communication precludes electromagnetic interference and compromising interception.
Optical fiber, however, has certain disadvantages not present in other forms of communication. Optical fiber is fragile rendering it subject to breakage while a wire communication system is stronger. Aside from breakage, optical fiber communication performance may be degraded by microcracks or microbends in the fiber generated by bending or other stresses imposed on the fiber. Such damage to an optical fiber not only reduces the fiber's long-term durability, but also causes losses in optical signal strength and content.
A typical optical fiber application involves packaging a continuous length of optical fiber inside a vehicle with one end of the fiber being attached to operational devices in the vehicle, attaching the other end of the fiber to a control or communications station at the launch site, launching the vehicle, and conducting two-way communication with the vehicle during its flight.
The problem is to provide a reliable and compact means for packaging the optical fiber in the vehicle which will minimize stresses on the fiber to preclude adverse effects on communication performance and which will permit reliable deployment of the fiber during flight of the vehicle. The use of wire for guidance or control of launched vehicles is known. U.S. Pat. Nos. 3,114,456 to Billiard, 3,156,185 to Hermann et al. and 3,319,781 to Simpson et al. are examples of such uses. The devices of these patents, however, are not directed to use of optical fiber as the communication medium. As noted above, the characteristics of optical fiber present difficulties not involved in use of wire for communication. The patents do teach the use of bobbins on which the wire is wound, but the fragility of optical fiber requires specialized winding on a bobbin that minimizes communication losses as well as permitting free streaming from the vehicle without clumping or knotting.
The subject invention provides a method of winding a continuous length of optical fiber on a bobbin for use in a moving or launched vehicle. The winding method minimizes stresses imposed on the fiber while permitting free streaming of the fiber from the vehicle. Other objects and advantages of the invention will be set forth in part in the description which follows, and in part will be apparent from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims.